SUBMITTED BY

ABHISHEK PANDEY

In this project we show the performance of MIMO-OFDM system in Rayleigh Fading Channel

MIMO-OFDM system is very popular technique for mobile communication now a day’s .We compares Ergodic and Outage Capacity , with taking various numbers of Transmitting and Receiving antennas and various performance measures such as SNR, BER etc.

MIMO-OFDM, Ergodic Capacity, BER, SNR Outage Capacity

Ever-increasing demands in communication industry towards wireless

Challenges: - to improve spectral efficiency

- efficient bandwidth utilization

- economical Signal Processing algorithms - high speed processing h/w

- Multiple i/p multiple o/p antenna array

- Used to increase data

rates, improve capacity and BER (bit error rate) of the system

- Typically used with OFDM so as to suit best needs in next generation comm. i.e. “4G”

Diagram of a MIMO wireless transmissionsystem.

SU-MIMO (Single User - MIMO) this utilizes MIMO technology to improve the

performance towards a single user. 

MU-MIMO (Multi User - MIMO) this enables multiple users to be served

through the use of spatial multiplexing techniques.

Definition

The first OFDM schemes presented in 1966

Development of OFDM over years

- Converts a frequency selective channel into a parallel collection of frequency flat sub channels

- Orthogonal frequency division multiplexing uses bandwidth efficiently

- Improves multipath fading issues

- Reduces the effect of ISI (inter-sub carrier interference)

OFDM System block Diagram

It distributes the data over a large number of carriers that are spaced apart at precise frequencies.

This spacing provides the "orthogonality" in this technique which prevents the demodulators from seeing frequencies other than their own.

◦ Two conditions must be considered for the orthogonality between the subcarriers.

Each subcarrier has exactly an integer number of cycles in the FFT interval.

The number of cycles between adjacent subcarriers differs by exactly one.

STTD (space time transmit diversity)

SM (spatial multiplexing)

AMC (adaptive modulation & coding) with modulation techniques such as QPSK, 16-QAM, 64-QAM

H-ARQ (Hybrid automatic repeat request)

Shared access and MAC (medium access control) used for scheduling packet access with Qos

Coupling MIMO and OFDM concepts to improve data rates in downlink of wireless communication networks.

Analyzing the performance and building a prototype of Wireless WAN’S using MIMO-OFDM

Use of adaptive loading algorithms such as Chows and Compello’s.

Employing SVD (singular value decomposition) method to increase the performance incase of MIMO

Survey, Implementation and performance analysis of existing MIMO

Learning s/w and h/w

Developing efficient algorithms

Software synchronization development

Various candidate coding and receiver strategies

Identification of Equipment

Implementation of prototype

The results obtained from these tests indicate very good performance for the MIMO-OFDM prototype.

Concept is proving to be very robust in highly dispersive channels

Cost reduction is being investigated through various methods

Simulation results show that at any given BER the adaptive SISO system will be outperformed by the adaptive MIMO system

Other future work areas involve the improvement of MIMO processing complexity and practical implementation issues.